I. Field of the Disclosure
The technology of the disclosure relates generally to a secure digital (SD) interface.
II. Background
Mobile communication devices have become common in current society. The prevalence of these mobile devices is driven in part by the many functions that are now enabled on such devices. Demand for such functions increases processing capability requirements and generates a need for more powerful batteries. Within the limited space of the housing of the mobile communication device, batteries compete with the processing circuitry. The competition for space between the components that provide the increased functionality and the battery that powers those components contributes to continued pressure to minimize power consumption so as to maximize available battery power.
One of many sources of inadvertent power consumption lies in the conductors that connect power consuming components to the power source. That is, such conductors have a resistance inherently present, and this resistance consumes power. One technique to reduce such inadvertent power consumption is to shorten the distance between the power source and the power consuming element.
Conductive path length is generally within the control of the product designer for conductors within the product. However, many products are now capable of being connected to peripherals. For example, smart phones may be connected to external speakers, external monitors, external keyboards, or the like. Desktop computers may be connected to smart phones, speakers, remote memory devices, or the like. In many cases, power may be transferred between the host and the peripheral device. The product designer rarely has control over the length of the cable that is used to connect the host to the peripheral. Because many such cables are approximately a meter (or more) long, the voltage levels for signals on such cables are typically several volts. In many cases, a standards body (e.g., Joint Electron Device and Engineering Council (JEDEC), USB-IF, Inc., SD Card Association) publishes a standard which sets forth minimum voltage levels for such connectors and/or cables. When applied to a mobile device such as a smart phone, the required voltage levels create large demands on the batteries of the mobile device. Additionally, higher level voltages may increase electromagnetic interference (EMI).